[citation needed] Gallwas, a native of California, first showed an interest in climbing in junior high school.

[6] In 1951, Gallwas began climbing with members of the Sierra Club from Southern California, including Royal Robbins and Don Wilson.

[9]: 311 [10][11] Robbins showed little interest in desert climbing, so Gallwas teamed with Wilson and Mark Powell to make a series of pioneering first ascents of sandstone spires in the American Southwest.

[9]: 312–316 [16][17][18] The Regular Northwest Face of Half Dome ascent was the first Grade VI climb in the United States.

[19] In the early 1950s, most American climbers imported climbing equipment from Europe or acquired it from US Army surplus.

In 1972, Gallwas served as a spokesperson for the adoption of voluntary consensus standards for laboratory medicine as the Food and Drug Administration began to regulate the medical device industry.

Gallwas is credited with collecting and displaying Arnold Beckman's earliest inventions that helped launch the electronic revolution in the chemical and biological sciences.

The inventions are displayed at the Arnold and Mabel Beckman Center of the National Academies of Science and Engineering in Irvine, CA.